Method of and means for priming a liquid pump



y 1964 A. D. ROBSON 3,140,665

METHOD OF AND MEANS FOR PRIMING A LIQUID PUMP z lwdm A'TTOQNEYS July 14 1964 RQBSON 3,140,665

METHOD OF AND MEANS FOR PRIMING A LIQUID PUMP Filed March 29, 1963 2 Sheets-Sheet 2 A won! y pnvuoob/a OBSON ATTORNEYS United States Patent 3,140,665 METHOD OF AND MEANS FOR PRIMING A LIQUID PUMP Anthony Dinwoodie Robson, .Epping, England, assignor to The British Oxygen Limited, London, England, a

British company Filed Mar. 29, 1963, Ser. No. 268,874 Claims priority, application Great Britain Apr. 11, 1962 Claims. (Cl. 10387) This invention relates to a method of and means for priming a liquid pump of the rotary type, and particularly,'but not exclusively, to a rotary pump driven by an electric motor which is cooled during running by a fan directly coupled to and rotating with the motor.

Pumps of this type are frequently used to pump liquified gases having boiling points substantially below atmospheric temperature, such as, for example, liquid oxygen. Owing to the very low boiling points of such liquified gases, any residual liquid left in a pump which is not in operation tends to vaporise and thus to cause vapour locking of the pump when it is restarted. It is therefore desirable that the pump should be completely filled with liquid when the pump driving unit restarts the pump, in order to avoid damage to the pump. It may also be desirable when the pump is stopped to ensure that as much residual liquid is removed from the pump as possible, in order to avoid the deposition as solid of any water or water vapour contained in the gas.

It is an object of the present invention to provide a method of and means for priming a liquid pump of the type specified which does not involve any mechanical or electrical contrivance and does not require that the pump should be touched by hand, and which can equally be used for clearing residual liquid from the pump after normal pumping has ceased.

According to one aspect of the present invention, a method of priming a liquid pump of the rotary type comprises rotating the pump by directing against the blades of a fan connected to the pump drive shaft a plurality of jets of a compressed gas so as to cause the fan to rotate.

According to a second aspect of the invention means for priming a liquid pump of the rotary type comprises a fan connected to the pump drive shaft and a plurality of nozzles adapted to be connected to a supply of compressed gas, each nozzle being arranged to direct a jet of the compressed gas against the blades of the fan so as to exert a force thereon in a direction to cause the fan to rotate.

The pump is preferably driven by a fan-cooled electric motor, in which case the nozzles may be arranged to direct the compressed gas against the blades of the cooling fan to rotate it. If the pump is driven by other means, a small fan may be mounted on the pump drive shaft to achieve the same result.

The nozzles may be carried by a tubular manifold of circular form mounted concentrically with and surrounding the fan, the manifold being adapted to be connected to a source of compressed gas. Conveniently, the manifold may consist of a length of tube closed at one end and adapted at the other to be connected to the source of compressed gas and bent into a circular form.

One embodiment of the invention as applied to a rotary pump driven by a fan cooled electric motor is illustrated in the accompanying drawings, in which:

FIGURE 1 is an end view of the cooling fan of the motor and the priming means of the invention, the casing of the motor being removed;

FIGURE 2 is a section along the line II-II of FIG- URE 1, showing the motor casing in place;

FIGURE 3 is an end view of one of the nozzles shown in FIGURE 1; and

3,140,665 Patented July 14, 1964 FIGURE 4 is a diagrammatic view showing the arrangement of pump, motor and fan.

Referring to FIGURES 1, 2 and 4, the rotary pump 9 is driven by an electric motor 10 (FIGURE 2 and FIG- URE 4) by means of a drive shaft 11 on which is mounted a fan 12 having blades 13, which acts to cool the motor 10 when the latter is in use. As shown in FIGURE 2, the motor and fan arm are housed within a casing 14.

A tubular manifold 15, formed from a length of tube bent into a circular form and closed at one end 16 and provided at the other end with a connection 17 by which it may be connected to a supply of compressed gas, is mounted within the casing 14 by means of brackets 18 in such a manner that the manifold 15 is concentric with and surrounds the fan 12. Four nozzles 19 are mounted on and communicate with the interior of the manifold, the nozzles being directed inwardly at an angle such that jets of compressed gas issuing therefrom will strike the blades 13 of the fan 12 and exert a force thereon having a component at right angles to the plane of the blades. As shown in FIGURE 3, the nozzles are each provided with an orifice 20 in the form of a slit, so as to direct a concentrated jet of compressed gas on substantially the full width of the blades 13.

In operation, when it is required to prime the pump, the manifold 15 is connected to a source of compressed gas, which issues through the orifices of the nozzles 19 in the form of concentrated jets which strike the fan blades 13 and thus cause the fan to rotate. Since the motor 10 is directly coupled to the pump drive shaft, this will rotate also and operate the pump. By a suitable selection of the pressure and quantity of the compressed gas supplied, and the number, size and angle of the nozzles, the pump may be rotated at a speed sufiicient to ensure the clearance of vapour from the pump. The electric motor 10 can then be switched on without fear of damage, the supply of compressed gas discontinued and the pump run normally. Rotation of the drive shaft 11 by means of the compressed gas jets issuing from the nozzles 19 will at the same time, determine whether the pump can rotate freely, or whether its rotation is hindered for any reason, again safeguarding the pump.

Similarly, when pumping has stopped and the electric motor 10 has been switched off, the fan 12 can be rotated by means of the compressed gas jets issuing from the nozzles 19 so as to remove as much residual liquid as possible from the pump, and thereby to minimize the amount of vaporisation taking place while the pump is not in use. This is particularly useful when the vaporised gas contains water vapour which would freeze and be deposited on the working parts of the pump.

While in the embodiment illustrated in the drawings, only four nozzles 19 are employed, a larger number of nozzles may be used if desired, these being spaced at appropriate intervals around the manifold 15. By suitable selection of the number and size of the nozzles, the angle at which they are mounted, and the pressure and quantity of the compressed gas supplied thereto, the present invention can be applied to pumps of varying sizes.

While it is preferred to use nozzles having slit-shaped orifices as shown in the drawings, nozzles of any other suitable shape may be used, if desired.

While the compressed gas used to provide the gas jets will usually be compressed air, any other compressed gas may be used should a supply be easily available, provided, of course, that it does not react with the liquid being pumped, or with the materials of construction of the motor or fan.

What I claim as my invention and desire to secure by Letters Patent of the United States is:

1. Means for priming a liquid pump of the rotary type, comprising an electric motor having a drive shaft coupled to said pump, a cooling fan mounted on said drive shaft adjacent to said motor, a common casing enclosing said motor and said fan, a tubular manifold concentric with and surrounding said fan, a plurality of nozzles surrounding and directed: towards said fan and carried by and communicating with said tubular manifold, and means connecting said manifold to a supply of compressed gas feeding said nozzles, each said nozzle being arranged to direct a jet of the compressed gas against the blades of said fan so as to exert a force thereon in a direction to cause said fan to rotate.

2. Means according to claim 1, wherein said manifold is in the form of a tube closed at one end and having at the other end means connecting said manifold to said supply of compressed gas, said tube being bent into a circular form.

3. Means according to claim 2, wherein each of said nozzles has a slit-shaped orifice having a length suflicient 4 to direct a jet of compressed gas over substantially the whole width of the fan blades.

4. Means for priming a liquid pump of the rotary type comprising an electric motor having a drive shaft coupled to said pump, a cooling fan mounted on said drive shaft adjacent said motor a common housing enclosing said motor and said fan, a plurality of nozzles surrounding and directed towards said fan, and a supply of compressed gas feeding said nozzles, each said nozzle being arranged to direct a jet of the compressed gas against the blades of said fan so as to exert a force thereon in a direction to cause said fan to rotate.

References Cited in the file of this patent UNITED STATES PATENTS 

1. MEANS FOR PRIMING A LIQUID PUMP OF THE ROTARY TYPE, COMPRISING AN ELECTRIC MOTOR HAVING A DRIVE SHAFT COUPLED TO SAID PUMP, A COOLING FAN MOUNTED ON SAID DRIVE SHAFT ADJACENT TO SAID MOTOR, A COMMON CASING ENCLOSING SAID MOTOR AND SAID FAN, A TUBULAR MANIFOLD CONCENTRIC WITH AND SURROUNDING SAID FAN, A PLURALITY OF NOZZLES SURROUNDING AND DIRECTED TOWARDS SAID FAN AND CARRIED BY AND COMMUNICATING WITH SAID TUBULAR MANIFOLD, AND MEANS CONNECTING SAID MANIFOLD TO A SUPPLY OF COMPRESSED GAS FEEDING SAID NOZZLES, EACH SAID NOZZLE BEING ARRANGED TO DIRECT A JET OF THE COMPRESSED GAS AGAINST THE BLADES OF SAID FAN SO AS TO EXERT A FORCE THEREON IN A DIRECTION TO CAUSE SAID FAN TO ROTATE. 